New septic system smells, and just wait until summer

Q: We have lived in our home for 27 years. Last year we had to install a new conventional septic system, as the old one was beginning to fail. About three months after the new installation, we started smelling a septic aroma around the yard when there was little or no wind. I traced it to the vent pipe on the roof. The installer was called, and he "opened up the system" for a look but said all is well. I asked whether something could be added to the system such as bacteria, etc., and he said I should not add anything.

The smell continues and will be more irritating, I suspect, in the summer, when we normally would have guests on the patio. Do I have an easily fixable problem, or do I have a faulty installation?

A: A septic tank is a septic tank. They all smell, and nothing can be done about that. They all need to be vented through the roof, via the plumbing system, to prevent dangerous levels of methane and other gases. A methane explosion in that buried nasty-bin or your plumbing pipes would not be pretty, so let me gently suggest avoiding the temptation to plug the vents.

Typically, the smell from a sewer or septic tank is noticed from the roof only in passing, and goes away as the wind or weather conditions change. Why the smell became noticeable, or if/how this is connected at all to the new installation, is not known to me or others I contacted in the industry (given that it was a conventional gravity system).

Without literally digging in, this is almost impossible to diagnose from a distance. The only lame advice I can provide is to run water from a hose down the vents to see whether this lessens the stench. Otherwise, it may take an up-close and personal visit from a respirator-clad indagator.

Readers, do you have any suggestions for this person to reduce the smell?

Q: Our condo has a big ol' hot-water storage tank wrapped in asbestos, too big to take out through any existing door. The expansion tank (to the boiler) needs replacement, according to the city, so we are looking to replace the expansion tank and the big ol' storage tank, which, because of the asbestos, has to be left in place until we are swimming in extra cash and can pay for removal.

A contractor suggests a 120-gallon commercial tank for replacing it; our boiler generates 4 gallons a minute, or 243 gallons an hour. We are worried that the new storage tank may be too small — it looks so much smaller than the behemoth we have. The contractor says we are fine for the 20-25 residents (in 14 units) we have. The contractor says we'd all have to be showering at the same time with washing machines on to begin to drain the system.

Some of us think we likely are wasting energy reheating all the water in the present old storage tank! Also, each unit is heated separately, old and new boiler handle water heating for hot-water use only, not building heating.

A: You have a tank capacity of 120 gallons, plus an additional 240 gallons of boiler production (4 gallons per hour x 60 minutes) every hour, if I understand you correctly. Within any given hour, you have 360 gallons of hot water at your disposal or, put another way, 6 gallons per minute to use for the first hour.

Water can come out of a boiler at 155 degrees or so. A shower cuts it down to about 100-105. A water-saving showerhead uses a nominal 2 gallons per minute — actual hot water used is going to be around 1.2 or so, after factoring in the cold to cut the temperature. The average shower by a non-teenager is, what, six minutes? Six times an even more-conservative 1.5 is 9 gallons per shower. Fourteen units times 9 gallons each is 126 gallons.

Four people could take continuous showers, and you would not even drain the tank down — this, of course, if everyone has reasonable showerheads and not straight-pipe dinosaurs from the '60s.

I believe you all could take showers within an hour, do the laundry and still have enough to do the dishes. And save money doing it. Go for it.

Darrell Hay answers readers' questions. Call 206-464-8514 to record your question, or e-mail dhay@seattletimes.com. Sorry, no personal replies. More columns at www.seattletimes.com/columnists.